Some computers permit the computer to perform a process during boot by which the computer authenticates a user of the computer prior to completion of the boot process. Authenticating a user prior to completion of the boot process is referred to as “preboot authentication.” Preboot authentication may be performed by the computer's basic input/output system (BIOS) code. Modifying the BIOS code to add new types of authentication mechanisms (e.g., retinal scan) unfortunately is time-consuming and expensive.